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We present results of first-principles non-equilibrium Green’s function calculations for current-voltage (IV) characteristics of the electrode/HfO2/electrode model systems. In order to investigate the effect of the electrode materials on the IV characteristics, we considered two transition metals for electrode, Ta and W, which are both body-centered-cubic elemental metals but have different valence numbers. We simulated the ON state by placing oxygen vacancies in the HfO2 layer while the OFF state was modeled with HfO2 without oxygen vacancies. At the OFF state, no electric current flowed for -1 V up to +1 V, as expected. At the ON state, however, we found that the absolute current for the Ta electrode was twice as large as that for the W electrode. The analysis of the IV characteristics shows that the electronic coupling between Ta and HfO2 is substantially stronger than that between W and HfO2. Our study demonstrates the importance of the matching between electrode and insulator materials to achieve a high ON- to OFF-current ratio in ReRAMs at a low bias.

High performance a-Si solar cells were developed. A conversion efficiency of 11.5% was achieved for a textured TCO/p-SiC/in/Ag structure with a size of 1 cm2 using the high quality i-layer fabricated by a new consecutive, separated reaction chamber apparatus. A conversion efficiency of 9.0% was obtained with a size of 10cm × 10cm. A high quality a-SiGe:H:F, which is a new narrow bandgap material for a-Si solar cells, was fabricated by a glow discharge decomposition of SiF4 + GeF4 + H2.

A photo-CVD method was investigated in order to improve the interface properties of a–Si solar cells. A conversion efficiency of 11.0% was obtained with a solar cell in which the p-layer is fabricated by the photo-CVD method. a-SiGe:H films were fabricated by the photo-CVD method for the first time as a narrow bandgap material for multi-bandgap a-Si solar cells.

Wide-gap a-Si:H films with device quality (Tauc’s optical gap > 1.9eV, σph under AMI.5, 100mW/cm2 illumination ≥ 10−5, Ω−1cm−1, a σph/σ a≥106) have been fabricated. These films are deposited at low substrtate temperatures (TS≤80°C ) either by diluting SiH4 with H2 or optimizing the plasma parameters in a capacitively–coupled RF plasma–CVD reactor. Reduction in the SiH2 bond density and the ESR spin density are also observed. In this study, good film quality is always accompanied by a small deposition rate. Furthermore, σph is nearly the same if the deposition rate and Ts is the same, regardless of other deposition parameters. This suggests that the surface reactions or structural relaxations at the film-growing surface can produce high–quality a–Si:H films even at low TsS, if the deposition rate is low. Results in thermal annealing, light exposure, and solar cell performance confirm that these films have device quality and wide bandgap.

The acceptor binding energy is calculated to find out the best acceptor impurity in InN, GaN and AlN. Be is predicted to be the shallowest acceptor and the next are Mg and Zn. Group IV elements such as C or Si are very deep. Band lineup is calculated to be ΔEc : ΔEv = 2.1 eV : 0.76 eV = 0.73 : 0.27 = 2.8 : 1 for GaN/AlN and ΔEc : ΔEv = 0.88 eV : 0.66 eV = 0.57 : 0.43 = 1.3 : 1 for GaN/InN. GaN is grown on GaAs and GaP-coated Si substrate by MOCVD. GaAs intermediate layer gives better GaN compared to GaP intermediate layer. It is suggested that the lower bulk modulus of GaAs than that of GaP gives this difference.

N and B codoped 6H-SiC epilayers were grown by the closed sublimation method, the growth rate of which was as high as 100 mm/h. Donor acceptor (DA) pair emission at different temperatures was investigated for two samples with different B concentrations. The integrated photon count obtained from the photoluminescence (PL) spectra of the sample having high B concentration increases with temperature. To estimate the internal quantum efficiency, we measured the PL integrated photon counts of GaN at 10 K as a reference. The integrated PL photon count of 6H-SiC DA-doped epilayer at 250 K is almost comparable to that of GaN at 10 K, which is thought to be almost 100% because of the freezing of the nonradiative recombination at low temperature. This result implies that the internal quantum efficiency of the 6H-SiC DA-doped epilayer exceeds 95%.

Planar Pt/AlGaN/GaN Schottky barrier diodes (SBDs) have been characterized by capacitance-voltage and capacitance deep-level optical spectroscopy measurements, compared to reference Pt/GaN:Si SBDs. Two specific deep levels are found to be located at ∼1.70 and ∼2.08 eV below the conduction band, which are clearly different from deep-level defects (Ec - 1.40, Ec - 2.64, and Ec - 2.90 eV) observed in the Pt/GaN:Si SBDs. From the diode bias dependence of the steady-state photocapacitance, these levels are believed to stem from a two-dimensional electron gas (2DEG) region at the AlGaN/GaN hetero-interface. In particular, the 1.70 eV level is likely to act as an efficient generation-recombination center of 2DEG carriers.

Whole-genome scans have identified Dmo1 as a major quantitative trait locus (QTL) for obesity
and dyslipidaemia in the Otsuka Long Evans Tokushima Fatty (OLETF) rat. We have produced
congenic rats for the Dmo1 locus, using marker-assisted speed congenic protocols, enforced by
selective removal of other QTL regions (QTL-marker-assisted counterselection), to efficiently
transfer chromosomal segments from non-diabetic Fischer 344 (F344) rats into the OLETF
background. In the third generation of congenic animals, we observed a substantial therapeutic
effect of the Dmo1 locus on lipid metabolism, obesity control and plasma glucose homeostasis. We
conclude that single-allele correction of an impaired genetic pathway can generate a substantial
therapeutic effect, despite the complex polygenic nature of type II diabetic syndromes.

The melt of Bi–Sr–Ca–Cu–O (BSCCO) was quenched by splatting using iron plates, resulting in formation of the glassy plates (0.3–0.7 mm thickness). The plates were converted into superconductors by reheating in air. The critical temperature, Tc, depends on the thickness. The change in Tc is discussed in terms of the difference in the amount of oxygen absorption and in crystallization behavior of the glassy plate during the reheating process between the glassy phase in the interior and that around the surface. It was found that high-Tc glass-ceramic thin plates can be prepared by controlling the amount or the rate of oxygen supply.

Cu2+-containing SiO2 and Al2O5 · 9SiO2 glasses were prepared by the sol-gel method and heated under reducing conditions to precipitate small-sized Cu and Cu2O erystals. Cu2+ ions incorporated in SiO2 glass were reduced by heating in N2 to precipitate Cu2O and in H2 to precipitate Cu microcrystals with diameters of about 5 to 15 nm. Microcrystalline Cu-precipitated glass showed an optical absorption band at 560 nm and its third-order nonlinear susceptibility was 1.25 × 10−10 esu, which originated from the enhancement by the surface plasmon resonance of Cu particles. In contrast, Cu2+ ions incorporated in Al2O3 · 9SiO2 glass remained unchanged after heating in the reducing gas atmospheres.

Bi–Sr–Ca–Cu–O (BSCCO) superconducting whiskers (2212 phase) were prepared by heating in air the compacted specimens of the mixtures of melt-quenched Bi2SryCa2Cu4Al1Ox powders and alumina powders. Formation of the whiskers depends on the composition and the applied pressure of the compacts. The optimum composition of the melt-quenched products for preparing the long whiskers is Bi2Sr2Ca2Cu4Al1Ox. Superconducting whiskers <1 mm in length (2212 phase) containing an excess amount of copper were grown numerously from the specimen compacted at 20 MPa; long whiskers (2212 phase) of 1–5 mm in length were obtained from that compacted at 180 MPa. These whiskers showed diamagnetic signals below Tc ≃ 80 K.

Pipes or hollow cylinders in the Bi-Sr-Ca-Cu-O system were found to be fabricated easily by inspiring or sucking the low viscosity melt into a cold silica glass tube. The outer part of the cast rod-like melt solidified, and the inner hot low-viscosity part of the rod melt was expired. The precursor pipes were reheated at 800 °C for 50 h in air, resulting in the formation of superconducting (Tc = 87 K) pipes which were of smooth surface without machining and high bending strength (100–150 MPa).

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